You have an agent. What do you actually hand it? “Something useful” is not a unit of work, and neither is “an AI”. This site uses five words for the layers in between, and they are worth getting straight, because each layer answers a different question.
A role is the bundle of responsibility: what function should this agent perform for you? A job is one recurring responsibility inside the role. A use case, also called a play, is a concrete way to execute a job in a specific context: trigger, inputs, steps, output. A skill is a reusable capability the agent needs along the way. A tool is the external service a skill or play connects to. One running example carries through the whole page: a Chief of Staff agent whose job is meeting preparation.
After the vocabulary, three content types. Every entry in the directory carries one of them as a badge: agent job, AI workflow, or automation. The badge tells you how much judgement the setup hands to the model, which is the main thing to know before you let anything run on its own. Each badge on the site links back to the matching definition here.
A role answers: what function should this agent perform for you? It is a bundle of responsibility with a mission, boundaries, and expected outcomes, not a single task. Example: Chief of Staff, an agent that keeps your day, your commitments, and your decisions organized.
A job is one recurring responsibility inside a role. It is narrower than the whole role and produces an outcome you would recognize. Example: meeting preparation, one of several jobs the Chief of Staff owns next to the daily brief and commitment tracking.
A use case, also called a play, is a concrete way to execute a job in a particular context: a trigger, inputs, steps, and an output. Example: thirty minutes before an external meeting, the agent collects the calendar event, recent emails, and open tasks, then generates a one-page briefing. Most entries in this directory are plays.
A skill is a reusable capability or instruction the agent needs to perform one or more jobs, and it transfers between plays. Example: summarize an email thread, which the pre-meeting brief uses to condense the latest correspondence with the person you are about to meet.
A tool is the external service a skill or play connects to. Pick tools last, once the capability is clear, and do not force one vendor when several fit. Example: Gmail and Google Calendar supply the raw material for the pre-meeting brief.
The badge on each card and detail page says which kind it is. The distinction is about how much judgement you hand over, and therefore how much supervision the setup needs.
An agent job is an ongoing responsibility the agent carries with judgement. It reads context, decides, and adapts instead of executing fixed steps. Example from the directory: Full-Time AI Receptionist, an always-on agent that answers queries, qualifies leads, and books appointments.
An AI workflow is a defined, triggered, bounded flow with one or more AI steps inside: the steps are fixed, the model does the reading and writing. Example: Meeting Summary & Action Item Tracker, transcripts in, prioritized action items and Slack updates out.
An automation is deterministic: trigger in, action out, no model judgement at all. Example: Accounting Deadline Alerts, a daily check of filing deadlines that emails a colour-coded urgency list.